This invention relates to articles for the protection of living tissues. More particularly, it relates to articles which are useful in the protection of living tissues from attack by harmful agents such as lasers and microorganisms, said articles being comprised of hydrogels and, if desired, additional additives such as salts, colorants and medications.
Lasers have recently made a significant breakthrough as a preferred, in some, and the only modality, in other surgical areas. These areas of increasing use of lasers in surgery and other treatments include, e.g., otolaryngology, gynecology and ophthalmology.
Amongst the main advantages of lasers, in surgery, are their ability to incise and/or remove precisely controlled areas of tissue while permitting visual assessment of the procedure through use of an operating microscope. This visual assessment is facilitated by reduction of bleeding and absence of other instrumentation, which might block the surgeon's view, in laser surgery when compared to conventional surgical techniques.
Furthermore, if the blood vessels are sufficiently small they are sealed, by the laser, after incision. If some bleeding were to occur, for instance, in the case of larger blood vessels it can be efficiently stopped by coagulation using a defocused beam, the defocusing being accomplished by partial retraction of the focusing tip, i.e., by increasing the working distance of the laser beam.
Additional advantages of using lasers in surgery are the limitation of the area of undesireable tissue destruction and the zone of devitalized tissue, fewer post-operative complications and less post-operative pain and scar formation which might hinder healing. As a consequence hospitalization time is reduced.
Nevertheless, the use of lasers, in medical treatments and surgery, is not without disadvantages and hazards, chief among which are the danger of fire and the destruction of viable tissue on the margins, or periphery, of the operative site.
As a consequence normal drape procedures commonly used in laser surgery and treatment are of limited value and potentially dangerous. For instance, a fire hazard is especially present when wet Cottonoids (cotton gauze pads wet with saline) which are used to protect the surrounding tissues and organs from exposure to extraneous laser beams, whether direct or reflected, dry out and ignite due to the high inflammability of dry cotton or cellulosics. This is an always present danger due to the high levels of energy associated with laser beams. Thus, it is necessary for the surgical team to be constantly aware of that possibility and to keep the gauze moistened at all times.
Yet other problems arise in the use of drapes on compound surfaces, i.e. surfaces that are not smooth but rather have cavities and ridges, whereby the usual drapes do not conform to the surface topography thereby permitting gaps to be formed between the tissue surface and drape. These gaps permit the gathering of gases and/or heat therein which ultimately result in undesirable tissue damage.
An additional aspect of the fire hazard is that the laser beam will burn through most plastics or rubbers of which tubes for insertion into body cavities, e.g., endotracheal tubes, are constructed. Thus, the use of plastic or most rubber endotracheal tubes is contraindicated when surgery employing lasers is contemplated. Therefore red rubber tubing or steel, which are less sensitive to lasers, are used in the construction of endotracheal tubes. However, because endotracheal tubes prepared from such materials lack built-in cuffs, they do not make completely airtight seals with the organ walls. To get around that problem it has been necessary to place a separable cuff over the distal end of the tube which has, therefore, resulted in the addition of a balloon-filling tube, passed through the larynx, to an already crowded lumen.
Another problem, the destruction of viable tissue near the operative site is due to the fact that, during surgery using lasers, it is often impossible to concentrate the laser exactly and exclusively on the surgical site. For instance, the incident beam may have a larger diameter than the surgical site or part of the beam may be dispersed or reflected, although at a lower intensity, to a distance from the surgical site. This results in undesireable destruction of healthy tissue at the periphery of, and/or at a distance from, the surgical site. The damage occurs in the same manner as the surgery is effected, i.e., by ablative removal of the water (about 90%) and organic matter of which the tissue is comprised.
In another aspect, exposed tissue, such as in wounds or at operative sites, is vulnerable to attack by disease-causing microorganisms.
It is, therefore, desireable to protect the vulnerable tissues from attack by extraneous laser beams or disease-causing microorganisms while permitting air and moisture to get to the tissue and facilitate the healing process.
However, when such tissue is protected by the usual type of sterile dressing dessication of the tissue ensues. It has, therefore, been found advantageous to cover such vulnerable tissue with dressings that have been wet with water or aqueous solutions of medications. Here again, the afore-mentioned Cottonoids have been used for construction of the dressings. However, use of these prior art dressings has not been without problems due to their limited absorption of the saline solution, facile dessication and poor structural integrity at high fluid contents, whereby it is possible for the pads to disintegrate and portions thereof to infiltrate the wound.
It has now been found that the articles of the instant invention obviate the above problems thereby providing for enhanced tissue protection during laser-effected surgery and treatments and against microorganism attack on exposed and vulnerable tissue whereby healing of the wounds is facilitated.